South Korean researchers have developed a glucose monitor embedded in a soft contact lens that can measure glucose levels.

While it is not the first lens to be developed that monitors glucose levels, the researchers say the device addresses a number of pre-existing complications regarding these lenses.

The lens works by measuring glucose in tears and transmitting the data wirelessly to a handheld device. So far in tests on animals no signs of discomfort have been observed.

Unlike previous lenses, which the researchers believe were too rigid, and the electronics too brittle, the new device is more stable, comfortable and less prone to breaking.

Lead study author Jang-Ung Park, of the Ulsan National Institute of Science and Technology in South Korea, added that previous attempts also hindered vision and were liable to damage theeye.

Among the newer advances include the stretchable nature of the circuits, which means it can be turned over.

An LED display has also been embedded in the lens, which emits a non-intrusive light if glucose levels become too high. The LED display can be emitted into the eye of the user or into the opposite direction.

"The integration of this display into the smart lens eliminates the need for additional, bulky measurement equipment," said the researchers.

"The resulting soft, smart contact lens provides real-time, wireless operation, and there are in vivo tests to monitor the glucose concentration in tears (suitable for determining the fasting glucose level in the tears of diabetic patients) and, simultaneously, to provide sensing results through the contact lens display."

Park revealed that there are still challenges remaining, and the lens is yet to be trialled on humans. Therefore it will most likely not be available commercially for at least five years.